Problem 729. Flag largest magnitude swings as they occur

Created by Doug Hull

Solve Later

{"relationships":[{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/document","targetMode":"","relationshipId":"rId1","target":"/matlab/document.xml"},{"relationshipType":"http://schemas.mathworks.com/matlab/code/2013/relationships/output","targetMode":"","relationshipId":"rId2","target":"/matlab/output.xml"}],"parts":[{"partUri":"/matlab/document.xml","relationship":[],"contentType":"application/vnd.mathworks.matlab.code.document+xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<w:document xmlns:w=\"http://schemas.openxmlformats.org/wordprocessingml/2006/main\"><w:body><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>You have a phenomenon that produces strictly positive or negative results.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[delta = [1 -3 4 2 -1 6 -2 -7];]]></w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>Marching through this list from beginning to end, mark a value with -1 if it is the greatest magnitude negative yet seen (strictly greater, not equal). Mark it with a one if it has the greatest magnitude in the positive direction (strictly greater, not equal). Just use a 0 if neither of these conditions have been met.</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"text\"/></w:pPr><w:r><w:t>The result for the above example would be:</w:t></w:r></w:p><w:p><w:pPr><w:pStyle w:val=\"code\"/></w:pPr><w:r><w:t><![CDATA[result = [1 -1 1 0 0 1 0 -1]]]></w:t></w:r></w:p></w:body></w:document>"},{"partUri":"/matlab/output.xml","contentType":"text/xml","content":"<?xml version=\"1.0\" encoding=\"UTF-8\" standalone=\"no\" ?><embeddedOutputs><metaData><evaluationState>manual</evaluationState><layoutState>code</layoutState><outputStatus>ready</outputStatus></metaData><outputArray type=\"array\"/><regionArray type=\"array\"/></embeddedOutputs>"}]}

Solve

Solution Stats

1620 Solutions
625 Solvers

Last Solution submitted on Jan 18, 2022

Last 200 Solutions

Problem Comments

3 Comments

3 Comments

Kevin Hellemans on 18 Sep 2013

The phrasing might be a bit ambiguous, as magnitude swing could also be thought of as delta(i-1)-delta(i) instead of just delta(i). Nonetheless fun problem!

Abhishek Jain on 16 Sep 2016

Nice question.

Abir Hasan on 1 Aug 2018

Nice problem

Solution Comments

Solution 1279961

1 Comment

1 Comment

yurenchu on 2 Oct 2017

Flawed solution; fails (for example) when 0

Solution 1076760

1 Comment

1 Comment

sjoerd on 7 Dec 2016

Officially not correct because it assumes that the first entry of x is 1, which is true for all testcases

Solution 778930

1 Comment

1 Comment

yurenchu on 2 Oct 2017

Flawed solution; fails when delta(1)<0, or when 0

Solution 377059

1 Comment

1 Comment

Alex Buczynsky on 9 Oct 2016

This is genius lololol

Solution 178349

1 Comment

1 Comment

Konstantinos on 13 Jun 2013

great solution Gwendolyn

Solution 118419

1 Comment

1 Comment

J.R.! Menzinger on 1 Nov 2012

Very nice the construct to avoid (for example) meshgrid!!

also the use of 'minus' to avois the use of double(...)-double(...)

Very interesting!

J.R.!

Problem Recent Solvers625

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Problem 729. Flag largest magnitude swings as they occur

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers625

Suggested Problems

More from this Author52

Problem Tags

Community Treasure Hunt

Problem 729. Flag largest magnitude swings as they occur

Solution Stats

Last 200 Solutions

Problem Comments

Solution Comments

Problem Recent Solvers625

Suggested Problems

More from this Author52

Problem Tags

Community Treasure Hunt

Players